A current conveyor is an electronic amplifier that is used to transfer a current from a first circuit to a second circuit. The current conveyer prevents the second circuit from undesirably loading the first circuit's output current, and thereby interfering with operation of the first circuit. The current conveyer may have a unity current gain, in which case the current conveyer does not alter the magnitude of the current it passes. An ideal current conveyer has an infinite output impedance and zero input impedance. Of course, an ideal current conveyer cannot be realized with real world physical components. However, a high output impedance and a low input impedance can be realized in a current conveyer. A current conveyer with a resistive load at its output is referred to herein as a trans-impedance amplifier. A trans-impedance amplifier (TIA) is an amplifier that receives a current and outputs a voltage. In other words, a TIA is a current to voltage converter.
Current conveyers have a wide variety of uses, one of which is in a radio frequency (RF) transceiver. A direct conversion receiver (DCR) may be used in an RF transceiver to receive an RF signal. The DCR demodulates an incoming radio signal using synchronous detection driven by a local oscillator whose frequency is very close or equal to the carrier frequency of the intended signal. In a DCR, the RF is fed into a frequency mixer, and the frequency of a local oscillator is near the received signal's frequency, resulting in a demodulated output. A DCR may include one or more current conveyors.